From a sphere of electrical conductivity K two planes cut a piece such that first plane passes through the centre of sphere and second parallel to first one at distance `R//2` from centre then resistance between A and B

Options

A. `(1)/(piKR)`
B. `(sqrt3)/(piKR)`
C. `(ln3)/(2piKR)`
D. None

Answer

C

Explanation

`int(1)/(K).(dx)/(pi(R^(2)-x^(2)))`
`R_(T) = (1)/(k pi) int (dx)/((R^(2) - x^(2))) = (1)/(2K piR)` In (3)